The nrfutil mcu-manager command lets you upgrade firmware over Bluetooth® Low Energy connection using the ble subcommand. You can use this subcommand with devices running firmware that has support for Simple Management Protocol (SMP) using Bluetooth LE.
In the scenario below, two devices are used: one device programmed with the Bluetooth Controller role and one programmed with the MCUboot bootloader and SMP over Bluetooth LE support. The controller device is used to upload several images to the MCUboot-compatible device, and you can control each step of the update process: from uploading each image to marking them for testing.